Tension meaning to cover unique selling point briefly (8)
I believe the answer is:
suspense
'tension' is the definition.
(suspense can mean tension or uncertainty)
'meaning to cover unique selling point briefly' is the wordplay.
'meaning' becomes 'sense' (sense is a kind of meaning).
'to cover' means one lot of letters goes inside another.
'unique selling point briefly' becomes 'USP' (abbreviation; 'briefly' indicates a short form).
'sense' placed around 'usp' is 'SUSPENSE'.
(Other definitions for suspense that I've seen before include "Excitement and uncertainty about an outcome" , "State of nervous uncertainly" , "State of anxiety or excitement" , "Alfred Hitchcock was the master of it" , "State of anxious uncertainty while waiting (8)" .)